Sounds like further delving into the groups dynamics and relationships is what they are going for in Avengers 2

Quote:

Before Phase Three of the shared Marvel Universe kicks-off with Ant-Man in late 2015, The Avengers 2 will conclude the 2nd Phase earlier that same year. When asked about director Joss Whedon’s “go deeper, not bigger” comment, Feige said:

“I don’t know exactly what he meant when he said “deeper”. But, similar to Iron Man 3, we’re not saying, “Now it’s gotta be even bigger and more aliens come and there’s a giant monster!” The most exciting thing to us about the Iron Man franchise is Tony Stark and his journey. The most exciting thing to us about the Avengers franchise is the interaction amongst thosecharacters. It’s putting them in situations that you wouldn’t expect to see them in. It’s that kind of fun; and the relationships between the characters in the Avengers, which I loved. Almost whatever the heck else is happening is gravy in that franchise, because all I care about is Bruce and Tony, Tony and Steve, Widow and Bruce – and how Thor fits into it, because he’s always the outsider amongst outsiders. So I think that’s where the value lies. And going deeper amongst those characters in those relationships.”